Aspen ===== Current Keywords: LOW, MODERATE, avalanche danger, cross loaded, crusts, density, drifts, explosive, facets, powder , recrystallized, slabs, stabilizing, trough, weak layer, wind slabs, windloaded, Mountain Weather and Avalanche Forecast for the Aspen Zone Forecast Issued on 12/18/2007 4:10:03 PM Forecaster: Ann Mellick Weather Synopsis Generally zonal flow continues today with the passage of a weak disturbance. Clouds will stream over the area as the next fast-moving system approaches from the northwest. Moisture thickens late this afternoon with snow spreading across the state this evening. Snow coverage and intensity will increase overnight and continue through Wednesday morning as the trough moves overhead. Showers diminish and partial clearing occurs Wednesday night into Thursday morning, but will not last long. The next, and strongest in this series of storms, moves into the area Thursday night. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 15-20 22-27 17-22 Wind Speed(mph) 15-25 15-25 10-20 Wind Direction WSW SW WSW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 0-1 1-4 0-3 Snowpack Discussion Observers report a generally stabilizing snowpack, but don't let your guard down. Strong and steady winds have redistributed snow near and above treeline. Expect to find fresh wind slabs, sensitive drifts, and cross loaded terrain features on a variety of aspects on higher elevation slopes as well as on exposed areas below treeline. These slabs can be reactive on steep slopes where they are sitting on low-density powder or facets. Several explosive triggered hard and soft slabs slid in freshly loaded areas on Monday. Observers in the Ashcroft area this weekend found the weak basal layer on north and easterly aspects to be reactive in snow stability tests. The presence and thickness of this weak layer varies throughout the zone. Your snowpack observations should include a careful look for this persistent weak layer before you commit to steeper terrain, especially on higher elevation, shady aspects. Another round of storms will move through this week bringing new avalanche problems. Now is the time to think about what this new snow will be falling on and how it will bond. Surface crusts have formed on lower elevation sunny slopes while near-surface facets have formed on cooler aspects. These small, angular, recrystallized surface grains do not currently pose a problem. They are actually what we often refer to as recycled powder and make for great skiing while they remain on the surface. However, these grains tend to bond poorly and will become reactive with the addition of new snow load in the future. Keep this in mind as snow piles up this week. Avalanche Danger Above treeline the avalanche danger is MODERATE on all aspects. Near and below treeline, danger is MODERATE on slopes facing west, northwest, north, northeast, and east. The danger is LOW on other aspects. Unstable windloaded slabs are possible eon most steep slopes. High elevation, shady slopes may have a weak layer at the bottom of the snowpack at a perfect depth for human-triggering. Your backcountry observations are very helpful to our forecasts. If you are traveling around Aspen Zone, we would love to know what you're seeing. Drop us a quick [57]e-mail with your observations from this area or any other. Front Range =========== Current Keywords: CONSIDERABLE, MODERATE, avalanche danger, cross loaded, drifted, drifts, human triggered, human triggered avalanches, natural, natural avalanches, path, powder. , slab, slabs, start zones, trough, wind loaded, wind slabs, Mountain Weather and Avalanche Forecast for the Front Range Zone Forecast Issued on 12/18/2007 4:05:42 PM Forecaster: Ann Mellick Weather Synopsis Generally zonal flow continues today with the passage of a weak disturbance. Clouds will stream over the area as the next fast-moving system approaches from the northwest. Moisture thickens late this afternoon with snow spreading across the state this evening. Snow coverage and intensity will increase overnight and continue through Wednesday morning as the trough moves overhead. Showers diminish and partial clearing occurs Wednesday night into Thursday morning, but will not last long. The next, and strongest in this series of storms, moves into the area Thursday night. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 10-15 18-23 10-15 Wind Speed(mph) 15-25 20-30 20-30 Wind Direction WSW W W Sky Cover Mostly Cloudy Mostly Cloudy Mostly Cloudy Snow(in) 0-1 0 0-2 Snowpack Discussion A skier triggered a slide on the Little Professor slide path off Loveland Pass on Monday. The slide initiated on a wind loaded south aspect just below the ridge, cracking 1 to 2 feet deep. Several triggered and natural slides occurred near Loveland Pass over the weekend as well. They primarily slid on heavily wind loaded north and easterly aspects above treeline. Backcountry travelers also noted both human triggered and natural avalanches in the Cameron Pass area over the weekend. Two separate parties remotely triggered slides on northerly aspects near and below treeline, one on Seven Utes Mountain, the other off Clark Peak. Observers noted natural avalanches above treeline on the NE aspects of the Diamond Peaks and the W aspect of Clark Peak as well. Strong and steady winds have drifted and transported snow onto a variety of aspects above treeline. Expect to find fresh wind slabs, sensitive drifts, and cross loaded terrain features on higher elevation slopes as well as on exposed areas below treeline. Many of the new slabs formed on top of the older powder. This strong over weak configuration can be easily triggered with the additional weight of a backcountry traveler. Strong winds have drifted snow well down onto slopes and into start zones. This means you may get lured farther down a slope before a slide releases. Wind slabs are ripe for human triggering. Potential trigger points include areas where the slab thins out, near rock outcroppings and sub ridges. Don't let it be you! Practice sound decision making and avoid crossing on or below wind loaded slopes. Avalanche Danger The avalanche danger for the Front Range zone is CONSIDERABLE on northwest, north, northeast, east, and southeast aspects near and above treeline. Human triggered avalanches are probable on steep wind loaded slopes. On south, southwest, and west aspects and all aspects below treeline, the danger is MODERATE. Unstable slabs are possible on steep slopes. Grand Mesa ========== Current Keywords: avalanche danger, crusts, melt-freeze, settled, shear, stabilized, surface hoar, trough, Mountain Weather and Avalanche Forecast for the Grand Mesa Zone Forecast Issued on 12/18/2007 4:11:04 PM Forecaster: Ann Mellick Weather Synopsis Generally zonal flow continues today with the passage of a weak disturbance. Clouds will stream over the area as the next fast-moving system approaches from the northwest. Moisture thickens late this afternoon with snow spreading across the state this evening. Snow coverage and intensity will increase overnight and continue through Wednesday morning as the trough moves overhead. Showers diminish and partial clearing occurs Wednesday night into Thursday morning, but will not last long. The next, and strongest in this series of storms, moves into the area Thursday night. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 15-20 27-32 17-22 Wind Speed(mph) 10-20 5-15 5-15 Wind Direction SW SW WSW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 0-3 1-4 1-4 Snowpack Discussion The snowpack in the Grand Mesa Zone has settled and stabilized since the last storm. Our forecaster in the area noted widespread 2mm surface hoar covering the snow on Tuesday. In places, this surface hoar is sitting on stiff wind crusts. This is a bad combination with new load. Surface hoar is notoriously weak in shear and will not support a very large load before failing. Lower elevation sunny slopes likely have melt-freeze crusts, which will not bond well with new snow either. The bottom line: as the snow piles up, the avalanche danger will rise as these surfaces become reactive with new load. Avalanches will likely be limited to surface snow and are not expected to step down. Be aware of changing conditions during the incoming storms. Avalanche Danger We have insufficient data to rate the avalanche danger in the Grand Mesa Zone. Please send observations from this or any other zone to [57]caic@qwest.net San Juan North ============== Current Keywords: LOW, MODERATE, avalanche danger, cross loaded, crusts, density, drifts, facets, powder , recrystallized, slabs, stabilizing, trough, wind slabs, Mountain Weather and Avalanche Forecast for the Northern San Juan Mountain Zone Forecast Issued on 12/18/2007 4:15:56 PM Forecaster: Ann Mellick Weather Synopsis Generally zonal flow continues today with the passage of a weak disturbance. Clouds will stream over the area as the next fast-moving system approaches from the northwest. Moisture thickens late this afternoon with snow spreading across the state this evening. Snow coverage and intensity will increase overnight and continue through Wednesday morning as the trough moves overhead. Showers diminish and partial clearing occurs Wednesday night into Thursday morning, but will not last long. The next, and strongest in this series of storms, moves into the area Thursday night. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 10-15 23-28 12-17 Wind Speed(mph) 15-25 10-20 15-25 Wind Direction SSW SW W Sky Cover Mostly Cloudy Mostly Cloudy Decreasing Snow(in) 0 1-3 0-2 Snowpack Discussion Reports of fresh avalanche activity in the NSJ Zone have all but stopped. Observers report a generally stabilizing snowpack with backcountry travelers skiing a variety of aspects and slope angles without incident. Don't let this make you complacent though. Weak layers still lurk on north and easterly aspects. Additionally, winds have changed the snowpack, stripping snow from some areas while depositing it in others. Winds have blown from the southwest to west to north and back again. This means that you can expect to find fresh wind slabs, drifts, and cross loaded terrain features on a variety of aspects on higher elevation slopes as well as on exposed areas below treeline. These slabs may be reactive on steep slopes where they are sitting on low-density powder or facets. Another round of storms will move through this week bringing new avalanche problems. Now is the time to think about what this new snow will be falling on and how it will bond. Surface crusts have formed on lower elevation sunny slopes while near-surface facets have formed on cooler aspects. These small, angular, recrystallized surface grains do not currently pose a problem. They are actually what we often refer to as recycled powder and make for great skiing while they remain on the surface. However, these grains tend to bond poorly and will become reactive with the addition of new snow load in the future. Keep this in mind as snow (hopefully) piles up this week. Avalanche Danger The avalanche danger for the Northern San Juan is MODERATE on all aspects and elevations except SE-S-SW aspects near and below treeline where the danger is LOW. Unstable slabs are possible on steep terrain. San Juan South ============== Current Keywords: LOW, avalanche danger, crown, crusts, faceting, facets, settle, stabilize, surface hoar, trough, weak layers, Mountain Weather and Avalanche Forecast for the Southern San Juan Mountain Zone Forecast Issued on 12/18/2007 4:16:24 PM Forecaster: Ann Mellick Weather Synopsis Generally zonal flow continues today with the passage of a weak disturbance. Clouds will stream over the area as the next fast-moving system approaches from the northwest. Moisture thickens late this afternoon with snow spreading across the state this evening. Snow coverage and intensity will increase overnight and continue through Wednesday morning as the trough moves overhead. Showers diminish and partial clearing occurs Wednesday night into Thursday morning, but will not last long. The next, and strongest in this series of storms, moves into the area Thursday night. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 12-17 25-30 13-18 Wind Speed(mph) 10-20 10-20 15-25 Wind Direction SW WSW W Sky Cover Mostly Cloudy Mostly Cloudy Decreasing Snow(in) 0 0-2 0-2 Snowpack Discussion Recent mild weather helped the snowpack to settle and stabilize. However, north and easterly aspects still hold weak layers such as facets and buried surface hoar. Last weekend, a skier or snowboarder triggered a slide in the Hourglass, a NNW facing aspect near Wolf Creek Pass. The crown measured roughly 2 feet deep by 30 feet wide and was triggered under a large rock outcropping. This serves as a reminder that pockets of instability do exist. Now is a great time to enjoy conditions, but do it safely. Work into steeper terrain gradually, reevaluating the snowpack often. Low avalanche danger does not mean no avalanche danger, so make decisions accordingly. Another round of storms will move through this week. Now is the time to think about what this new snow will be falling on and how it will bond. Observers in the Purgatory area noted widespread surface hoar development on the northern half of the compass while on the southern half, angled slopes have formed surface crusts. Observers have also noted near surface faceting in cool areas. Currently, none of these layers pose a problem. However, they do tend to bond poorly with fresh snow and will become reactive with the addition of new snow load in the future. Keep this in mind as snow piles up this week. Avalanche Danger The avalanche danger is LOW on all aspects and at all elevations. There are isolated areas where you could trigger avalanches on steep slopes. You will want to examine the snowack carefully before committing to steep terrain. Sangre de Christo ================= Current Keywords: avalanche danger, cross loaded, density, drifts, facets, powder , settle, slabs, stabilize, trough, wind slabs, Mountain Weather and Avalanche Forecast for the Sangre De Cristo Zone Forecast Issued on 12/18/2007 4:16:47 PM Forecaster: Ann Mellick Weather Synopsis Generally zonal flow continues today with the passage of a weak disturbance. Clouds will stream over the area as the next fast-moving system approaches from the northwest. Moisture thickens late this afternoon with snow spreading across the state this evening. Snow coverage and intensity will increase overnight and continue through Wednesday morning as the trough moves overhead. Showers diminish and partial clearing occurs Wednesday night into Thursday morning, but will not last long. The next, and strongest in this series of storms, moves into the area Thursday night. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 10-15 25-30 13-18 Wind Speed(mph) 20-30 20-30 15-25 Wind Direction WSW WSW WSW Sky Cover Partly Cloudy Increasing Mostly Cloudy Snow(in) 0 0-1 0 Snowpack Discussion Recent mild weather helped the snowpack to settle and stabilize. Don't let this make you complacent though. Weak layers still lurk on north and easterly aspects. Strong and persistant winds have changed the snowpack, stripping snow from some areas while depositing it in others. Winds have blown from the southwest to west to north and back again. This means that you can expect to find fresh wind slabs, drifts, and cross loaded terrain features on a variety of aspects on higher elevation slopes as well as on exposed areas below treeline. These slabs may be reactive on steep slopes where they are sitting on low-density powder or facets. Work into steeper terrain gradually, reevaluating the snowpack often. Avalanche Danger We have insufficient data to rate the avalanche danger in the Sangre de Cristo Zone. Please send observations from this or any other zone to [57]caic@qwest.net Sawatch ======= Current Keywords: CONSIDERABLE, LOW, MODERATE, avalanche danger, cross loaded, crossloading, drifting, drifts, facets, powder. , settled, slab, slabby, slabs, trough, wind drifting, wind slabs, Mountain Weather and Avalanche Forecast for the Sawatch Range Zone Forecast Issued on 12/18/2007 4:08:35 PM Forecaster: Ann Mellick Weather Synopsis Generally zonal flow continues today with the passage of a weak disturbance. Clouds will stream over the area as the next fast-moving system approaches from the northwest. Moisture thickens late this afternoon with snow spreading across the state this evening. Snow coverage and intensity will increase overnight and continue through Wednesday morning as the trough moves overhead. Showers diminish and partial clearing occurs Wednesday night into Thursday morning, but will not last long. The next, and strongest in this series of storms, moves into the area Thursday night. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 10-15 20-25 10-15 Wind Speed(mph) 20-30 20-30 15-25 Wind Direction W W W Sky Cover Mostly Cloudy Mostly Cloudy Mostly Cloudy Snow(in) 0-1 1-3 0-2 Snowpack Discussion Since our last storm over a week ago, there has been lots of drifting and transport of snow above treeline. Expect to find fresh wind slabs, sensitive drifts, and cross loaded terrain features on higher elevation slopes as well as on exposed areas at treeline. Many of the new slabs formed on top of the older, recycled powder. This strong over weak configuration can be easily triggered by the additional weight of a backcountry traveler, especially when you are at the slab margin. A forecaster near Monarch Pass on Monday found settled powder and recycled powder in near and below treeline areas, especially on westerly aspects. He found slabby, wind effected snow near and above treeline. North through east through south aspects were heavily loaded from strong steady winds. New snow from incoming storms will likely not bond well with any of these surfaces. Basal facets are becoming more pronounced on high elevation, shady slopes. There remains potential to trigger large, deep avalanches in these spots. Avalanches are becoming more difficult to trigger, but the structure of the snowpack still dictates a cautious approach to backcountry travel. Use caution and sound decision making while traveling in the backcountry today. Avalanche Danger The avalanche danger is MODERATE with pockets of CONSIDERABLE on northwest, north, northeast, east, and southeast aspects above treeline. Be cautious near steep slopes that have recent wind drifting and loading. The danger is MODERATE on all aspects at treeline and other aspects above treeline. Again, watch for steep slopes with crossloading or drifting. Below treeline the danger is LOW on all aspects. Steamboat ========= Current Keywords: avalanche danger, collapsing , cross loaded, crossloaded, crusts, drifts, faceted, facets, human triggered avalanches, powder , recrystallized, slabs, sugary, trough, whumpfing, windslabs, Mountain Weather and Avalanche Forecast for the Steamboat and Parks Range Zone Forecast Issued on 12/18/2007 4:04:36 PM Forecaster: Ann Mellick Weather Synopsis Generally zonal flow continues today with the passage of a weak disturbance. Clouds will stream over the area as the next fast-moving system approaches from the northwest. Moisture thickens late this afternoon with snow spreading across the state this evening. Snow coverage and intensity will increase overnight and continue through Wednesday morning as the trough moves overhead. Showers diminish and partial clearing occurs Wednesday night into Thursday morning, but will not last long. The next, and strongest in this series of storms, moves into the area Thursday night. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 10-15 23-28 12-17 Wind Speed(mph) 15-25 15-25 15-25 Wind Direction W WSW WSW Sky Cover Overcast Overcast Mostly Cloudy Snow(in) 1-3 2-5 1-4 Snowpack Discussion The north to west to southwest winds over the past several days moved quite a bit of snow around. Expect to find fresh windslabs, sensitive drifts, and cross loaded terrain features on exposed higher elevation slopes in the Steamboat Zone. Observers on Buffalo Pass last weekend noted lots of whumpfing as well as a couple recent avalanches. These slid below treeline on steep north facing slopes off the Camel's Hump. Steep slopes that have wind affected slabs sitting on top of sugary facets continue to be the most likely place to trigger a slide today. This combination can be found on higher elevation northwest, north, northeast, and east aspects. Watch for signs of instability, such as collapsing and cracking, while traveling in the backcountry today. Human triggered avalanches remain possible on steep slopes where slabs over lie facets. You can move from relatively stable snow, lacking the faceted basal layer, to unstable snow over a short distance. Re-evaluate the snowpack often, and practice conservative decision making. Another round of storms will move through this week bringing new avalanche problems. Now is the time to think about what this new snow will be falling on and how it will bond. Surface crusts have formed on lower elevation sunny slopes while near-surface facets have formed on cooler aspects. These small, angular, recrystallized surface grains do not currently pose a problem. They are actually what we often refer to as recycled powder and make for great skiing while they remain on the surface. However, these grains tend to bond poorly and will become reactive with the addition of new snow load in the future. Keep this in mind as snow piles up this week. Avalanche Danger We have insufficient data to rate the avalanche danger in the Steamboat Zone. The most problematic areas are probably steep north, northeast, and east facing slopes that have old, weak snow underneath. Expect some crossloaded soft slabs on high elevation slopes. If you have any observations or data to share, please send them to [57]caic@qwest.net. Vail ==== Current Keywords: , CONSIDERABLE, LOW, MODERATE, avalanche danger, collapse, cornice, cross loaded, density, drifted, drifts, human triggered avalanches, natural, path, powder. , slab, slabs, start zones, trough, wind loaded, wind loading, wind slab, wind slabs, Mountain Weather and Avalanche Forecast for the Vail and Summit County Zone Forecast Issued on 12/18/2007 4:07:35 PM Forecaster: Ann Mellick Weather Synopsis Generally zonal flow continues today with the passage of a weak disturbance. Clouds will stream over the area as the next fast-moving system approaches from the northwest. Moisture thickens late this afternoon with snow spreading across the state this evening. Snow coverage and intensity will increase overnight and continue through Wednesday morning as the trough moves overhead. Showers diminish and partial clearing occurs Wednesday night into Thursday morning, but will not last long. The next, and strongest in this series of storms, moves into the area Thursday night. Weather Tuesday Night Wednesday Wednesday Night Temperature(°F) 8-13 17-22 10-15 Wind Speed(mph) 15-25 15-25 15-25 Wind Direction WSW WSW W Sky Cover Mostly Cloudy Overcast Mostly Cloudy Snow(in) 0-1 1-3 0-3 Snowpack Discussion Conditions vary quite a bit across the Vail/Summit Zone. News of fresh natural and triggered avalanche activity continues to come in from the eastern part of the Zone, specifically in the Loveland Pass area. A skier triggered a slide on the Little Professor slide path on Monday. The slide initiated on a wind loaded south aspect just below the ridge, cracking 1 to 2 feet deep. Several triggered and natural slides occurred near Loveland Pass over the weekend as well. They primarily slid on heavily wind loaded north and easterly aspects above treeline. Winds have blown from the northeast, north, west, and southwest. Observers note lots of complex wind loading and some cornice collapse at ridgelines. West slopes are largely stripped while wind slabs, sensitive drifts, and cross loaded terrain features pepper most other aspects on higher elevation slopes as well as on exposed areas below treeline. Fresh slabs can be reactive on steep slopes where they are sitting on low-density recycled powder. Observers on Monday noted that fresh wind slabs 20-30cm deep are not bonding well with the underlying wind slab. Strong winds have drifted snow well down on slopes and into start zones. This means you may get lured farther down a slope as the slab thickness demonstrates strength. On the western side of the zone, observers noted few of the signs of instability that are omnipresent on the eastern side of the zone. It has received much less wind, therefore resulting in less slab development. Continue to travel smart, and avoid crossing on or below wind loaded slopes. Ride one at a time and have your escape routes planned before approaching any slope in question. Avalanche Danger The avalanche danger for the Vail Summit zone is MODERATE with pockets of CONSIDERABLE on north through east through south aspects above treeline. MODERATE on all aspects at treeline and LOW below treeline. Human triggered avalanches are probable above treeline on north through east through south aspects. Unstable slabs are possible on steep slopes. The danger is not as great in the western part of the zone where winds have been lighter.